Low-Power ASK Detector for Low Modulation Indexes and Rail-to-Rail Input Range

A high-performance ultrahigh-frequency amplitude shift keying (ASK) detector for low-power radio-frequency (RF) receivers is proposed. The circuit is based on a high-gain common-source topology with a feedback loop that provides adaptive biasing. Hence, high sensitivity and rail-to-rail input operation are achieved along with low power consumption. The detector was implemented in a standard 130-nm complementary metal-oxide-semiconductor technology. Sensitivity measurements demonstrate correct detection of a 2-Mb/s ASK-modulated 915-MHz signal with a peak level and a modulation index of around 200 mV and 5%, respectively, which means an envelope signal amplitude of as low as 5 mV. The circuit draws less than 3.4 μA from a 1.2-V power supply while operating with rail-to-rail RF variations and modulation indexes from 5% to 100%. This performance makes the detector suitable for batteryless systems with RF energy harvesting.